[RTTY] Some basic RTTY questions

[Jeff Stai]

On Sat, May 31, 2014 at 10:37 AM, Michael Rapp <mdrapp at gmail.com> wrote:

> Would there be a problem with the PTT line from the Signalink and the PTT
> line from the W3YY box being connected to the PTT pin on the FT-950 at the
> same time?  They obviously wouldn't be keyed/carry a signal at the same
> time.
>

I have never seen a PTT radio input that couldn't be attached to multiple
devices (I suspect there is the inevitable older rig that had an issue, but
certainly not a late model Yaesu).

It's almost always a "wire-OR" situation with a pullup resistor in the
radio just waiting for any signal to pull it low and key the rig.

Similarly at the devices these are wired in an open-collector arrangement,
just for this reason. I would expect both those devices to have open
collector drivers (or open drain) on the PTT - as opposed to an active
driver pulling up the signal - but it wouldn't hurt to double check.

Good luck - 73 jeff wk6i


-- 
Jeff Stai ~ wk6i.jeff at gmail.com
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